He said there were many options for investors in the market. They could make their own choice according to what they thought was value for money, he said.

"Fisher Funds expects that over time real scale will put general modest downward pressure on fees - very few providers have that scale today but KiwiSaver will change this over time. In that respect all Fisher Funds fees are under review constantly as scale and competitive forces change," he said.

"It would not be acceptable to Fisher Funds clients for an increase in the fixed management fee at this time, notwithstanding current strong returns. In our opinion Management fees have to be set with a through the cycle view and must be reasonable in both the good and not so good times."

Fees were highlighted by FMA head of regulation Liam Mason at this week's Commission for Financial Capability summit.

He said there were a range of options in the market and members were switching between them - but it was not clear that they were doing so in a way that was logically following value-for-money considerations.

He said the industry needed to do what it could to make costs as clear as was humanly possible - recent changes to the way fees were described in annual statements did not necessarily go far enough, he said.

There should be an obligation put on everyone who "wore the KiwiSaver badge" regarding the services they offered consumers, he said.